Adsorption Of Azo Dyes Research Articles

Adsorption and Fenton oxidation of azo dyes by magnetite nanoparticles deposited on a glass substrate

Fenton oxidation is an efficient and useful method for wastewater treatment. To increase overall reaction efficiencies and inhibit environmental impacts, developing advanced catalysts are crucial in this matter. The main goal of this study was to investigate the catalytic activity of the magnetite (Fe2+Fe23+O42−, FeFe2O4, or Fe3O4) nanoparticles (NPs) coated borosilicate glass on the color removal of basic red 18 (BR18) and acid red 8 (AR88) azo dyes by adsorption and Fenton oxidation reaction. The efficiency of powder magnetite NPs was also tested to compare to magnetite NPs coated borosilicate glass. The effect of solution pH (2.5–9.0), catalyst loading (0.25–3.0 g/L), and dye concentration (0.1-0.3 mM) were tested to achieve maximum color removal efficiency using powder magnetite NPs. The color removal efficiencies were measured 44% at pH 9.0 and 76% at pH 3.5 for adsorption and Fenton oxidation of BR18 dye (0.1 mM). Moreover, the color removal efficiencies were measured 81% at pH 3.5 and 100% at pH 6.0 for adsorption and Fenton oxidation of AR88 dye (0.1 mM). The effect of hydrogen peroxide (H2O2) concentration (2.5–25 mM) was also optimized and 10 mM was found optimum H2O2 dosage for Fenton oxidation. However, magnetite NPs coated borosilicate glass enhanced maximum 77% and 82% color removal efficiencies for adsorption and Fenton oxidation of BR18 dye. Maximum 86% and 100% color removal efficiencies were obtained for adsorption and Fenton oxidation of AR88 dye. Stability of the powder magnetite NPs and magnetite NPs coated borosilicate glass catalyst was also investigated. The reusability of the catalyst showed that magnetite NPs coated borosilicate glass could be used at least 3 times without significant loss of activity compared to powder magnetite NPs for Fenton oxidation. The characterization of the catalyst was carried out using scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray powder diffraction (XRD), and zeta potential analyses before and after adsorption.

Study of Thermodynamic and Kinetic Adsorption of Azo Dyes on Different Adsorbent Surfaces

Study of Thermodynamic and Kinetic Adsorption of Azo Dyes on Different Adsorbent Surfaces

Optimization, isotherm and kinetics studies of azo dye adsorption on eggshell membrane

Eggshell membrane (ESM) was used as an adsorbent for adsorption of reactive red 195 (RR195) and reactive black 5 (RB5) dyes from aqueous solutions. The experimental conditions were optimized via batch system experiments for maximum azo dyes removal. Adsorption of the dyes was pH dependent highly, and the maximum adsorption of RR195 and RB5 occurred at pH 3.0 and 2.0, respectively. For both dyes, the adsorption process was seen to be obeyed pseudo-second order kinetic and the Langmuir isotherm models. Maximum adsorption capacities (Qmax) of ESM for RR195 dye and RB5 were found as 76.9 and 333.33 mg g-1, respectively. The thermodynamic parameters were calculated and the adsorption of the dyes was found to be as exothermic and spontaneous. Moreover, the structural characterization of the ESM was performed by FTIR and SEM analysis.

Equilibrium and Thermodynamic Studys of Adsorption of Azo Dyes on The Local Bentonite Clay

Equilibrium and Thermodynamic Studys of Adsorption of Azo Dyes on The Local Bentonite Clay

Azo-dye adsorption activity of iron(III) loaded novolac-based network sorbents

Iron(III) loaded novolac-based network adsorbents 1 and 2 were studied for efficient removal of azo-dye pollutants from aqueous solutions. The adsorption behavior was evaluated by using methyl orange and orange-G as model azo dyes. The effect of parameters such as contact time and initial dye concentration on the adsorption of azo dyes was studied. The results showed that loading of Fe(III) onto the sorbent networks has noticeable effect on azo-dye sorption capacity. The adsorption equilibrium data were fitted to Freundlich isotherm model. Besides, the reusability of the dye loaded sorbents was investigated on adjusting pH of solutions.

Porous Eleocharis@MnPE Layered Hybrid for Synergistic Adsorption and Catalytic Biodegradation of Toxic Azo Dyes from Industrial Wastewater.

The effective treatment of industrial wastewater to protect freshwater reserves for the survival of life is a primary focus of current research. Herein, a multicomponent Eleocharis-manganese peroxidase enzyme (Eleocharis@MnPE) layered hybrid with high surface area (1200 m2/m3), with a strong synergistic adsorption and catalytic biodegradation (SACB), has been developed through a facile method. A combination of outer porous (Eleocharis) and inner catalytically active (MnPE) components of the hybrid resulted in highly efficient SACB system, evidenced by high removal rate of 15 kg m-3 day-1 (100%) and complete degradation of toxic Orange II (OR) azo dye into nontoxic products (gases and weak acids). The Eleocharis@MnPE layered hybrid efficiently degraded both OR in synthetic wastewater and also other azo dyes (red, pink, and yellow dyes) present in three different textile industrial effluents. For the industrial effluents, these were evidenced by the color disappearance and reduction in biological oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) of up to 97%, 92%, and 76%, respectively. Furthermore, reduced toxicity of treated wastewater was confirmed by decreased cell toxicity to 0.1%-1% and increased cell viability to 90%. We believe that designing a hybrid system with strong ability of SACB could be highly effective for industrial-scale treatment of wastewater.

Lanthanum enriched aminosilane-grafted mesoporous carbon material for efficient adsorption of tartrazine azo dye

Abstract For the first time the synthesis of mesoporous carbon of cubic structure modified with 3-aminopropyltriethoxysilane and lanthanum chloride, and its ability to remove tartrazine azo dye from aqueous solutions, have been described. The physicochemical properties of the adsorbent were characterized by X-ray diffraction, low-temperature nitrogen sorption, transmission electron microscopy, FT-IR spectroscopy and Boehm titration. The carbon functionalization was found to significantly change its porosity, structure ordering and acid-base character of its surface. The effect of different key parameters such as contact time, temperature, initial concentration and pH of azo dye solution on the effectiveness of tartrazine adsorption was evaluated. Sorption capacity of mesoporous material was found to increase with increasing initial dye concentration and contact time but decreases with increasing temperature of the system, from 25 to 60 °C. The effectiveness of tartrazine removal by La/CKIT-6-A material was compared with that of pristine carbon (CKIT-6) and the aminosilane-grafted sample CKIT-6-A. The introduction of lanthanum on the surface of sample functionalized with 3-aminopropyltriethoxysilane increased its sorption capacity towards tartrazine. The best fit to experimental data was obtained for the Langmuir isotherm model, suggesting homogeneous distribution of adsorption sites on the surface of mesoporous carbon. The adsorption kinetic data were well described with the pseudo-second-order kinetic model. On the basis of the detail analysis of the interactions between the carbon material and tartrazine, a mechanism of dye adsorption was proposed.

Adsorption of New Azo Dyes Derived From 4-Aminoantipyrine from Aqueous solution by A New Type of Activated Carbon: Equilibrium and Kinetic Studies

This study is aimed to the synthesis of new azo dyes starting with 4-Aminoantipyrine. The thermodynamic behavior of the dyes adsorption on a new kind of activated carbon prepared from (Asphalt : Polymer) mixtures are studied. The research involved the selection of the optimum conditions for the adsorption process by studying the factors affecting it such as the effect of adsorbent dose, contact time, initial concentration and temperature, the work also included the fitting of two models of isotherm equations (Freundlich, Langmuir isotherms) on experimental data of adsorption models under consideration. This study was carried at different temperature and at range of concentrations. The constants of these isotherms were used to describe the nature of the studied systems and the type of interaction between dye and carbon surface. Depending on the results obtained from adsorption study at different temperature, the values of thermodynamic functions of adsorption were calculated at different concentration, using the equilibrium constant which obtained from the ratio between the concentration of the adsorbed and the free dye in solution. The above results showed that, the adsorption of these dyes are of physical nature and the experiential data were better obeyed Langmuir isotherm. The study also involved employing four kinetic models on the experimental data; pseudo first order, pseudo second order, Elovich and intraparticle diffusion equations. The results of this study showed that, the adsorption system under investigation obeyed the Pseudo second order model and the intraparticle diffusion is not the only mechanism controlling the adsorption systems under study.

Immobilized CeO2 for adsorption of azo dye

Azo dyes are not efficiently removed in water treatment. So the development of excellent absorbent is significant important for environmental protection. In this study, ceria is successfully immobilized on 40-60 mesh sand by using a simple method of sol–gel. And then research the effect of absorption on azo dyes in waster using immobilized CeO2 (ICe). The ICe absorbent displays high removal efficiency for AB10 (one typical kind of azo dyes) in waste water. In addition, after absorbing, concentration and toxicity of azo dye decreased and the absorbent easily separation from water which indicates that the technique is a promising post-treatment process to improve water quality.

Adsorption of anionic food azo dyes from aqueous solution by silica modified with cetylpyridinium chloride

A silica modified by cetylpyridinium cations for the effective preconcentration of azo dyes from dilute aqueous solutions was proposed. The morphology of the modified silica was studied by SEM and it was shown that the modified silica surface has a 3D framework structure. The fixation of cetylpyridinium cations on the silica surface was confirmed by the diffuse reflectance infrared Fourier-transform spectroscopy method. Using the mathematical planning of the experiment via the method of Latin squares; the conditions for the adsorption of dyes have been optimized. It was found that the maximum dye adsorption occurs at pH 1.5–2.5 where azo dyes are in the ionic form with dissociated sulfo groups. The formation of ion pairs of azo dye anions and cetylpyridinium cations in solution was proved by spectrophotometry and on the surface by diffuse reflection spectroscopy. It is shown that adsorption isotherms are of the H-type and they are well described by the Langmuir equation. The maximum adsorption capacity of the modified silica with respect to azo dyes ranges from 2 to 9 μmol/g and depends on the geometric dimensions and spatial configuration of the dyes molecules. Thermodynamic studies have made it possible to establish the endothermic nature of adsorption. It is shown that the most effective eluent is 1.0 × 10−3 mol dm−3 solution of sodium dodecylsulfate in 0.1 mol dm−3 solution of NH3·H2O, and desorption itself occurs due to the destruction of ion pairs of dye anions with cetylpyridinium cations fixed on the surface.

Polymer-Decorated Filter Material for Wastewater Treatment: In Situ Ultrafast Oil/Water Emulsion Separation and Azo Dye Adsorption.

Aiming to realize the wastewater treatment of various pollutants simultaneously, a dual-functional poly(ether amine)-polydopamine (PEA-PDA)-modified filter material was fabricated in this work for in situ separation of stable oil-in-water emulsion and adsorption of anionic azo dyes. PEA and PDA could be copolymerized via the Michael addition reaction on a polyurethane sponge substrate firmly. The as-prepared filter shows superhydrophilic and underwater superoleophobic wettability. After being squeezed in a glass tube, the material could separate different kinds of stabilized oil-in-water emulsions with high flux and efficiency. Besides, the PEA-PDA copolymer endows the material with the ability to adsorb large amounts of anionic azo dyes during the separation of emulsions with good adsorption capacity. Moreover, adsorbed dyes in the filter material could be easily desorbed in base aqueous solution and the whole process is conducted under gravity without external aid. This dual-functional material shows great potential for the application in industrial field because of its ability for the complex wastewater treatment.

Polymer-hybrid silica composite for the azo dye removal from aqueous solution

The article presents a cost-effective approach to the preparation of polymer-hybrid silica composites in the form of spherical beads, a micrometer in size, which are easy to handle and completely water wettable. Taking into account the swelling phenomenon of the Amberlite XAD7 HP resin, tetramethoxysilane and [3-(2-aminoethylamino)propyl]trimethoxysilane were introduced into polymeric particles with different molar fractions, which was followed by their hydrolysis and condensation in the vapor phase; as a result polymer-amino-functionalized silica systems were formed. The article discusses the characteristics of the composites and their performance on the Cochineal Red A (Ponceau 4R) adsorption and desorption. The composite azo dye adsorption capacity is much higher (up to ×100) than for the parent polymer and reaches about 46 mg g−1. The desorption of azo dye from composites can be enhanced by the modification of the pH of the release medium. Thus, the described materials may be regarded as effective adsorbents for the colorant removal.

Optimized preparation of activated carbon from municipal sewage sludge and application to the adsorption of azo dye from aqueous solutions

In this study, the conditions for preparation of active carbon from municipal sewage sludge (MSS) were optimized from application to the efficient removal of the azo dye, Acid Orange 7 (AO7), from aqueous solutions. To maximize the adsorption capacity (response variable) of the MSS‐derived activated carbon (MSS‐AC), a 3 k Box–Behnken design based on response surface methodology was used to simultaneously optimize five important conditions (independent variables), that is, carbonizing temperature (400–600°C), carbonizing time (0.5–2.0 h), impregnation ratio (1.0–3.5 g KOH/g MSS), activating temperature (600–800°C), and activating time (0.5–2.0 h). The optimal conditions were established as carbonizing temperature: 509°C, carbonizing time: 1.25 h, impregnation ratio: 2.3 g KOH/g MSS, activating temperature: 681°C, and activating time: 1.21 h, with an overall desirability function of 0.991. Further, the effects of various key parameters (solution pH, ionic strength, adsorbent dosage, initial concentration, contact time, and temperature) on the adsorption of AO7 on the as‐synthesized MSS‐AC were elucidated through a series of batch experiments. Adsorption kinetics and isotherm studies revealed that the adsorption process is accurately described by the pseudo‐second order and Sips models. The theoretical maximum adsorption capacity of AO7 was found to be ~1410 mg/g at 25°C, which is superior to that of the other adsorbents reported to date. Additionally, the intraparticle diffusion model suggested that the adsorption was controlled by both external surface adsorption and intraparticle diffusion. Thermodynamic studies also suggested that the adsorption of AO7 by MASS‐AC is exothermic and is governed by physisorption. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S267–S276, 2019

Experimental and Atomic Modeling of the Adsorption of Acid Azo Dye 57 to Sepiolite

AbstractSepiolite is a hydrated magnesium silicate with a microporous and mesoporous structure. The fibrous morphology and the alternating blocks and tunnels along the fiber direction of sepiolite make it an ideal material to sequester a variety of organic and inorganic contaminants. The adsorption of various surfactants by organo sepiolites have been experimentally investigated. How this hydrophobic material adsorbs dye molecules at the atomic level, however, is a great mystery. For this reason, the present study focused on the adsorption of acid azo 57 dye molecules to modified sepiolite. For this purpose, the amenability of sepiolite to remove the anionic textile dye (acid azo red dye 57) was first studied in detail. Additionally, a typical cationic surfactant, hexadecyltrimethylammonium Br (HTAB), was used to modify sepiolite to increase the adsorption capacity. Zeta potential measurements on the sepiolite and the HTAB modified sepiolite were also carried out. Moreover, Density Functional Theory (DFT) studies were performed to understand the mechanism of the adsorption of dye molecules to natural and modified sepiolite surfaces. On the basis of the experimental studies, three general systems were theoretically examined: (i) HTAB molecules on sepiolite basal surfaces to represent four Si tetrahedra, (ii) neutral or charged acid azo red dye 57 molecules on sepiolite basal surfaces to represent four Si tetrahedra, and (iii) HTAB on the surface of neutral or charged acid azo red dye 57 molecules as a substrate. The results clearly indicated good agreement between the experimental studies and the theoretical computational DFT studies. For example, the double layer structure found in experimental studies was also demonstrated in DFT studies and confirmed increased adsorption in the presence of acid azo dye 57.

Ultrasound enhanced Azo Dye adsorption by Graphene Oxide Nanocomposite

Ultrasound enhanced Azo Dye adsorption by Graphene Oxide Nanocomposite

Azo dye adsorption on anthracite: A view of thermodynamics, kinetics and cosmotropic effects

The present paper presents anthracite – a low cost and naturally abundant coal – as a potential adsorbent of the azo dye Acid Yellow 42, evaluating parameters such as dye concentration, temperature and ionic strength. A thermodynamic and kinetic approach was also described. Interactions between the adsorbate and anthracite were described by isothermal titration as well. Anthracite was characterized by TGA/DTA, FT-IR, X-ray, TEM/EDS. The adsorption system anthracite-dye reached equilibrium in less than 10 min at room temperature, with a maximum adsorption capacity as high as 47 mg g−1. A multi-layer pattern is observed according to the Freundlich adsorption model and the adsorption kinetics is best explained by the pseudo-second-order model. A chemisorption phenomenon drives the initial process, followed by a multi-layer physisorption phenomenon between dye molecules, with a prevalence of electrostatic interactions. The adsorption of acid yellow 42 onto anthracite is a spontaneous (ΔadsG° = −11.68 kJ mol−1) and endothermic (ΔadsH° = 58.59 kJ mol−1) process, suggesting that the driving force to promote adsorption is the increase of the degree of freedom in the interface anthracite/solution (ΔadsS° = 70.26 kJ mol−1). The amount of AY immobilized at the surface of anthracite increased with the temperature rising, evidencing an endothermic process. Cations and anions influence the adsorption process, not obeying and following Hofmeister series, respectively. Ionic charge lead to increase Zeta potential. Therefore, anthracite highlights as a potential adsorbent material for azo dyes compared with other natural materials and some activated carbons.

Magnetic composite Fe3O4/CeO2 for adsorption of azo dye

In this paper, magnetic composite Fe3O4/CeO2 (MC Fe/Ce) was synthesized via CeO2 covered onto the surface of Fe3O4 by sol-precipitation method. The as-synthesized samples were characterized by FE-SEM, XRD, SEM-EDS and FT-IR spectrum. The pseudo-second-order (PSO) kinetic can describe well the adsorption of Acid black 210 (AB210) onto the as-obtained MC Fe/Ce of which the adsorption isotherm fits the Langmuir adsorption model better than Freundlich adsorption model. Furthermore, the maximum monolayer adsorption capacity of MC Fe/Ce is about 93 mg/g, which is 6 times more than that of commercial CeO2 for AB210. Moreover, the removal rate of the adsorbates for AB210 is 82.3% after first adsorption and still about 70% the fourth forth adsorption experiments within 120 min, which demonstrates that the obtained MC Fe/Ce has outstanding adsorption capacity and good stability. Additionally, the composite can be easily separated from aqueous solution in a few seconds with an external magnetic field due to its magnetic property, which is vital and has potential for its practical applications.

Real-Time Monitoring of Azo Dye Interfacial Adsorption at Silica-Water Interface by Total Internal Reflection-Induced Surface Evanescent Wave.

An interface research method based on total internal reflection induced evanescent wave (TIR-EW) is developed to monitor the adsorption behavior of azo dye at the silica-water interface. The monitoring system is constructed by employing silica optical fiber (SOF) as both charged substrate for dye adsorption and light transmission waveguide for evanescent wave production. According to the change of evanescent wave intensity and followed by Beer's law, the methylene blue (MB) adsorption behavior can be real-time monitored at the silica-water interface. Langmuir adsorption model and pseudo-first-order model are applied to obtain the related thermodynamic and kinetic data. The adsorption equilibrium constant ( Kads) and adsorption free energy (Δ G) of MB at the silica-water interface are determined to be (3.3 ± 0.5) × 104 M-1 and -25.7 ± 1.7 kJ mol-1. Meanwhile, this method is highlighted to isolate elementary processes of adsorption and desorption under steady-state conditions, and gives adsorption rate constant ( ka) and desorption rate constant ( kd) of 8585 ± 19.8 min-1 and 0.26 ± 0.0006 min-1 for 15 r/min flow rate. The surface interaction process is revealed and adsorption mechanism is proposed, indicating MB first adsorbed on Si-O- sites through electrostatic attraction and then on Si-OH sites through hydrogen bond with increasing MB concentrations. Our findings from this study provided molecular-level interpretation of azo dye adsorption at silica-water interface, and the results provide important insight into how MB adsorption can be controlled at the interface.

Carbon composite lignin-based adsorbents for the adsorption of dyes

Carbon composite lignin-based adsorbent were prepared through hydrothermal method with glucose as carbon source, calcium lignosulfonate and triethylene tetramine as raw materials, respectively. The optimum synthesis conditions were determined by investigating the addition of carbon and triethylene tetramine. The adsorbent was used for the adsorption of azo dyes Congo red and Eriochrome blue black R, and the five factors affecting the adsorption were discussed, including pH of dyes, initial concentration, adsorption time, adsorption temperature and adsorbent dosage. The corresponding adsorption mechanism such as pseudo first order kinetics, pseudo second order kinetics, intraparticle diffusion, Langmuir adsorption isotherm, Freundlich isotherm, Temkin isotherm, Dubinin-Radushkevich adsorption isotherm, thermodynamics were also studied. When the dye concentration is 40 mg L−1, Congo red and Eriochrome blue black R dye removal rates reach 99%. Moreover, the adsorption process of two kinds of dyes follow the pseudo second order kinetics and the Langmuir adsorption isotherm.

Azo dyes adsorption in fixed bed column packed with different deacetylation degrees chitosan coated glass beads

Chitosan with different deacetylation degrees (DD) was used to coat glass beads by dip coating technique, and the coated beads were applied in fixed bed adsorption of tartrazine and sunset yellow from aqueous solutions. Chitosan DD 85% was the best adsorbent in relation to the coating and bed performance for dye adsorption. The adsorption capacity increased with temperature increase as demonstrated by the equilibrium isotherms, which were performed in batch assays using chitosan coated glass beads; the data were suitably fitted by BET model (R2 > 0.95 and ARE < 5%). The best performance attained in the fixed bed assays was using chitosan DD 85%, being the breakthrough time of 90 min, the column maximum adsorption capacity around 60 mg g−1 and removal percentage of 50.4%. The breakthrough curves were well represented by Yoon–Nelson model (R2 > 0.95 and ARE < 10%). The elution efficiency was of 82% in the fourth adsorption–desorption cycle.